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Valence bond theory predicts that xenon will use _____ hybrid orbitals in XeOF4.


A) sp
B) sp2
C) sp3
D) sp3d
E) sp3d2

F) C) and E)
G) A) and B)

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In the valence bond treatment, a bond is formed when two 2p orbitals overlap side to side.

A) True
B) False

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Atoms of period 3 and beyond can undergo sp3d 2 hybridization, but atoms of period 2 cannot.

A) True
B) False

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Describe the bonding in ethylene (ethene, C2H4) according to valence bond theory. Be sure to indicate the orbital hybridization on the carbon atoms. Draw a diagram clearly showing at least one bond of each type which occurs in the molecule.

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The carbon atoms are sp2 hybridized, leaving the 2pz orbital on each carbon unhybridized. Overlap of one sp2 hybrid on each carbon and occupation of this region by an electron pair produces a C-C F1F1F1S1F1F1F10 bond. Overlap of the remaining four hybrid orbitals with 1s orbitals of four hydrogen atoms, produces four C-H F1F1F1S1F1F1F10 bonds. The unhybridized 2pz orbitals overlap laterally to produce a F1F1F1S1F1F1F10 bond which has two regions of electron density, above and below the C-C F1F1F1S1F1F1F10 bond. (Diagram needed.)

In applying molecular orbital theory, the bond order is calculated in the same way as with Lewis structures.

A) True
B) False

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When PCl5 solidifies it forms PCl4+ cations and PCl6- anions. According to valence bond theory, what hybrid orbitals are used by phosphorus in the PCl4+ cations?


A) sp
B) sp2
C) sp3
D) sp3d
E) sp3d2

F) A) and C)
G) A) and E)

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Valence bond theory is able to explain why molecular oxygen is paramagnetic.

A) True
B) False

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Explain what is meant by the term "bond order" and describe how it can be calculated using the information in a molecular orbital energy level diagram.

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The bond order in MO theory is the net n...

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Explain what is meant by a node (or nodal plane) in a molecular orbital and draw sketches of the following orbitals, indicating at least one nodal plane in each one. a. a * orbital b. a * orbital

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A nodal plane is a plane of zero electro...

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In the valence bond treatment, overlap of an s orbital on one atom with an sp3 orbital on another atom can give rise to a bond.

A) True
B) False

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True

A molecule with the formula AX4E uses _________ to form its bonds.


A) sp2 hybrid orbitals
B) sp3 hybrid orbitals
C) sp3d hybrid orbitals
D) sp3d2 hybrid orbitals
E) none of the above

F) A) and E)
G) B) and E)

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According to valence bond theory, which orbitals on N and H overlap in the NH3 molecule?


A) 2p on N overlaps with 2s on H
B) 2p on N overlaps with 1s on H
C) 2s on N overlaps with 1s on H
D) sp3 on N overlaps with sp on H
E) sp3 on N overlaps with 1s on H

F) A) and B)
G) B) and D)

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Which of the following statements relating to molecular orbital (MO) theory is incorrect?


A) Combination of two atomic orbitals produces one bonding and one antibonding MO.
B) A bonding MO is lower in energy than the two atomic orbitals from which it is formed.
C) Combination of two 2p orbitals may result in either or MOs.
D) A species with a bond order of zero will not be stable.
E) In a stable molecule having an even number of electrons, all electrons must be paired.

F) A) and D)
G) C) and D)

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Hybrid orbitals of the sp3d type occur in sets of four.

A) True
B) False

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According to valence bond theory, overlap of bonding orbitals of atoms will weaken a bond, due to electron-electron repulsion.

A) True
B) False

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Sketch the shapes of the 1s and 1s* molecular orbitals formed by the overlap of two hydrogen 1s atomic orbitals.

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11ec6d41_b4d1_c266_9cd1_172eeb...

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According to molecular orbital theory, what is the bond order in the O2+ ion?


A) 5.5
B) 5
C) 4
D) 2.5
E) 1.5

F) A) and C)
G) C) and D)

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What type of hybridization is needed to explain why ethyne, C2H2, is linear?

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a. What simple experiment could you perform to show that a substance is paramagnetic? b. What microscopic (atomic/molecular) feature must a substance possess in order to be paramagnetic? c. Can it be predicted whether or not all homonuclear diatomic ions, X2+, will be paramagnetic? Explain.

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a. Place a sample of the substance near a magnet; if it is attracted to the magnet, it is paramagnetic. b. The substance must have unpaired electrons in order to be paramagnetic. c. Yes, they will necessarily be paramagnetic since each will have an odd number of electrons.

The angles between sp2 hybrid orbitals are 109.5°.

A) True
B) False

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